Whiteboards, also known as dry erase boards, are commonly used in offices, schools, and other locations where a chalkboard might otherwise be found. Writings on a dry erase board are erasable by wiping lightly with felt, dry cloth or paper. Suitable whiteboard surfaces generally include a melamine, vinyl, polyethylene laminate, polyvinyl chloride or enamel resin layer affixed to a backing. Such whiteboards are characterized in that they have hard, white surfaces that are very smooth in appearance, and are essentially nonporous. Alternatively, a whiteboard may comprise a sheet of polymeric film such as an acrylic or UV curable resin. Of course each of these “whiteboard” materials may be used in other articles of manufacture such as plastic writing boards used in children's toys.
Coloring compositions are employed to mark a wide variety of substrates. In addition to hard surfaces such as whiteboards, the most commonly employed substrate is paper (or a paper-like material), which is produced in many qualities. In many respects, paper presents a superior writing surface. The surface of paper is generally smooth and even. Moreover, the porosity of paper assists the writing process by drawing the coloring composition into the paper matrix, promoting even application and smooth appearance. However, porous paper is not an ideal writing substrate for all applications. For example, many types of paper (e.g., newsprint, or the highly porous paper commonly employed in children's coloring books) are sufficiently porous to draw a coloring composition through the paper to create a mark on the surface opposite that desired, thereby rendering it difficult to employ both sides of a single sheet of paper. This is commonly referred to as “strike-through” of the ink. Moreover, inks which strike through (or bleed through) paper can actually leave marks on surfaces supporting the paper (such as succeeding sheets of paper in a book, clothing, furniture, and the like). Also, strike-through dulls or reduces the presentation of the color.
Efforts aimed at reducing drying time and strike-through of water-based marker inks have proven largely unsuccessful. Some commercially available inks reduce strike-through by incorporating additives which substantially increase the viscosity of the coloring composition. For example, hyperthermogelling inks incorporating a high amount of surfactants exhibit a phase change due to the evaporation of a given amount of water (e.g., U.S. Pat. No. 5,462,591). While such inks are useful for some applications (e.g., commercial printing presses), they are too viscous for use in common writing instruments, such as capillary markers with porous nibs.
One other area of marker ink technology that has undergone change over the past several years is that relating to pigments. The introduction of new pigments over this period has provided ink developers with the ability to produce wet markers having a variety of vivid and attractive colors. This increase in the availability of colors and hues in coloring compositions has fueled the demand for further improvements in the properties of wet markers, generally. One of the areas of crayon and ink marker development which has been affected by the foregoing may be characterized as the area of “special effects.”
One area of special effect is fluorescence. This property is obtained by the use of fluorescers, which are substances which emit electromagnetic radiation (usually as visible light) resulting from (and occurring only during) the absorption of radiation from some other source. Examples of pigments which fluoresce under daylight conditions are described in U.S. Pat. No. 3,939,093. Such fluorescent pigments have also been included in marking compositions, e.g., U.S. Pat. No. 3,057,806, which describes fluorescent crayons.
One U.S. patent which discloses special effect pigment compositions which comprise a combination of common pigments, phosphorescent pigments, and fluorescent pigments, is U.S. Pat. No. 4,725,316. These pigment compositions are alleged to be combinable with translucent plastics, resins, and natural and synthetic rubbers. However, there is no mention of their use in connection with liquid markers. U.S. Pat. No. 5,498,280 discloses a crayon marking coloring composition comprised of a mixture of phosphors and fluorescers in a polyethylene glycol wax binder, with no application to capillary markers. Neither prior art patent demonstrates a special effect liquid ink composition for use in a general purpose marker for writing on both soft and hard substrate surfaces.
In view of the foregoing problems, there exists a need for a special effect coloring liquid ink composition that is quick-drying and which exhibits limited or little strike-through when applied to porous papers such as coloring book paper. There is also a need for such compositions that are washable from skin and common fabrics. Furthermore, such compositions are needed which are suitable for use in common ink-based writing instruments (e.g., capillary markers). The present invention meets these needs and provides a low bleed coloring composition suitable for use in common ink-based marking instruments.